A first action that a mobile station performs is obtaining symbol synchronization to perform initial access to a predetermined wireless communication system. The present invention relates to the obtaining of the symbol synchronization.
According to a conventional method of obtaining symbol synchronization in an orthogonal frequency division multiplexing (OFDM) system, a transmitting base station assigns a single base sequence to a frequency resource available in a frequency area of a synchronization channel, and a receiving mobile station measures a correlation value between a time area signal of the synchronization channel and a received signal of the time area and regards a sample time having a highest correlation value as a symbol synchronization time.
However, according to the conventional method, performance of obtaining synchronization is deteriorated in an environment where a frequency offset is high.
Also, according to a conventional wireless communication system excluding a system based on the OFDM system, when a base sequence is assigned to a symbol section used for obtaining synchronization of a time area symbol, a size of the base sequence is required to be regular. However, according to the method of assigning the sequence having the regular size, performance of obtaining synchronization is also deteriorated in the environment where the frequency offset is high.
Accordingly, there is need for a frequency offset estimating apparatus and method that performs estimating of symbol synchronization as efficient as the conventional method in an environment where the frequency offset is small, and also performs estimating of the symbol synchronization better than the conventional method in an environment where the frequency offset is large.